This invention relates to fan or wheel pulling devices, and more particularly to an improved device which positively engages the hub of a fan or wheel for removal of the fan from a central drive shaft.
It is a commonplace occurrence, during repair or replacement of a fan or pulley wheel in such devices as a compressor, to remove the fan or wheel from the drive shaft. Traditionally, a hub of the fan or wheel is affixed to the shaft by one or more setscrews threadedly secured in holes in the hub and tightly engaging the periphery of the shaft.
To remove the hub from the shaft, the setscrews are first retracted and removed. Then, a conventional apparatus such as that described in U.S. Pat. No. 1,355,028 is placed about the hub. Gripping bolts extending through the housing of the prior art apparatus are then tightened to frictionally engage the periphery of the hub. A compression bolt, passing through the top of the housing and the central aperture of the hub, is rotated in engagement with the shaft, causing the housing and gripped hub to lift from the shaft.
The prior art devices do not grip simple, cylindrical hubs with sufficient force to ensure against slippage in cases where the hub is frozen to the shaft or where the end of the shaft expands due to oxidation over extended period of use. In such cases, it often becomes necessary to sever the hub, and thus destroy the hub in order to facilitate the removal of the hub from the shaft.
This and other disadvantages of the prior art are overcome by the present invention which provides a device for pulling an affixed hub from a drive shaft by positively securing the pulling device to the hub employing the one or more setscrew holes provided in the hub.
The device has a generally cylindrical, hollow housing of a sufficient internal capacity to accommodate the hub. One or more locking bolts extend radially through threaded holes in the wall of the housing and are of a sufficient length to engage the hub. A jacking bolt extends axially through a threaded opening in the top of the housing directly above and engageable with the shaft. At least one circumferential slot is located in the wall of the housing formed in registration with one of the threaded holes in the hub. A threaded engagement screw having threads compatible with the threaded setscrew hole is inserted through the slot and adapted to engage the setscrew hole when the setscrew is removed.
A locking nut is placed on the engagement screw for locking the engagement screw against the outer wall of the device in order to vary the effective length of the engagement screw and thus limit the penetration of the screw into the hub to avoid engagement with the shaft.
In order to aid visual alignment of the housing about the hub, one or more sighting apertures may be provided in the wall of the housing.
In a preferred embodiment of the invention, a pair of the locking bolts extend from diametrically opposite positions in the housing toward each other to engage a hub therebetween. A pair of the slots, spaced at approximately ninety degrees about the circumference of the housing, and a corresponding pair of engagement screws are employed to be screwed into the threaded holes in the hub.